a. Field of the Invention
The invention relates to a vehicle headlight device.
b. Description of the Related Art
Nowadays, various types of LED vehicle headlamps are commercially available. As shown in FIG. 8, U.S. Pat. No. 7,731,402 discloses a vehicle headlamp 100 having an LED light source 102, a primary optical light guide 104, and a secondary optical light guide 106. The optical light guide elements 104 and 106 focus and collimate light beams emitted from the LED light source 102 to form a light pattern suitable for a vehicle headlamp. Besides, two brightness enhancement films 110 and 112 perpendicular to each other are disposed on a side surface of the secondary optical light guide 106 to redirect and recycle light.
Further, U.S. patent publication No. 2009/0251917 discloses an illumination device including a light source, a light guide and two brightness enhancement films. The brightness enhancement films function to redirect and recycle light emitted from the light source. U.S. patent publication No. 2012/0314145 discloses a backlight device including a wedge-shaped light guide plate and a re-direction film with a prism array. The light guide plate is coated with a reflective layer at the bottom, and an end of the light guide plate is provided with a wavy surface. Light beams emitted from a light source pass through the re-direction film and are collimated to be substantially parallel to each other. U.S. patent publication No. 2010/0315833 discloses an optical system having a light input engine, optical elements, and two optical films arranged to be perpendicular to each other. Each optical film has a lenticular lens array to change light-emitting angles. Taiwan patent publication No. 201207452 discloses a light-collimating film having a base layer, multiple lenticular lenses and multiple prism structures. The lenticular lenses and the prism structures are disposed on opposite sides of the base layer, and their longitudinal directions are perpendicular to each other. U.S. Pat. No. 7,645,048 discloses an optical device including a light source, a light guide plate, a prism sheet, and a reflective sheet. The light guide plate has a first inclined surface and a second inclined surface, the reflective sheet is disposed under the light guide plate and is configured in a triangular shape corresponding to the first inclined surface and the second inclined surface of the light guide plate.
However, these conventional designs may encounter some problems, such as requiring specific optical lenses, failing to accurately control light-emitting angles, causing excessive stray light, or increasing the cost for a solution to heat-dissipation problems.